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Ambient Light Sensor - TEMT6000

Description: This is a small ambient light sensor that acts as an NPN transistor. The more the sensor is exposed to light, the stronger the base bias. Simple to use! Simple breakout board available below.

I’ve bought 4-5 of these for use in our lab, one is mounted on our sun tracker controller, and works great (using it with 4 photo-resistors to give the sun’s relative location and irradiance.) but the last 3 have been duds.. The diode reads either as on open or shorted circuit. We hook them up to arduino’s, so even a crossed wire hook up should only be 5V, which I don’t think can burn out a photodiode. Any idea what is happening? Here are pics of the good and bad sensor (https://plus.google.com/107935709908498477582/posts/5fXwMVz4Yfn ). Could overheating the board when soldering do this?

I usually solder @ 358°C, 3-4 seconds on the to-be-joined metals, then apply a solder bridge, then solder the other bit to join to the bridge (4-6 seconds total). But according to the datasheet these have a MAX time of 3 seconds with a MAX temp of 260°C. Which means I would probably destroy everyone I soldered using my ‘norm.’ If you’re like me then yes you probably overheated them…

I was wondering how bad temperature would affect this sensor. We are planning on using them to determine the brightness of the sunlight on livestock. We are in the south and the heat can get rather extreme. Also, I only have 3.3 volts available, will this work with a lower voltage? Thanks, Brian

Have a look at the datasheet directly from Vishay;
http://www.vishay.com/docs/81579/temt6000.pdf
Page 491 (don’t worry, there’s not actually that many pages in the document) has the current vs ambient temperature graphs you’re looking for.

Thanks so much. So, on a given day it could be 70 in the morning and 98 in the afternoon. Would I need to log temperature and do some sort of correction for the light measurement to be the same through out the day?

In that chart, the relative output is basically a multiplier, with 1.0 set to about 77F (25C).
For 70F, the multiplier is about 0.94.
For 98F, the multiplier is about 1.18.
Whether that is of actual concern depends on your application, though.

Thanks so much again for your help. This would be used for livestock behavior research. We have Kinetamaps that we are using for location and accelerometer to count steps and bites. We would like to add the ability to log the brightness of the sun. Basically, we are trying to determine at what sun intensity an animal seeks shade. So we would need the sensor to accurately record the brightness of the sun across all temperatures so that data recorded in the dead of winter is comparable to data that is recorded in the height of summer. Do you think this type of sensor is the right choice? If so, should I record temperature and use the multipliers to compensate for temperature?

Yes, you would have to record temperature as well ( which I’m guessing you may already be recording? ) and compensate accordingly.
However, I’m not sure this sensor is right for the purpose. The datasheet doesn’t really give the information I was looking for, namely the range of the sensor. However, the lux vs current graph only goes up to 1,000 lux. Broad daylight (not even counting the sun) is well into the tens of thousands of lux. On the other hand, the datasheet also mentions a maximum collector current of 20mA which, if the graph continues linearly, should be adequate even for full sunlight.
So this might be a question for the forums - get a few more eyes on it. If nothing else, I’m sure there will be alternatives suggested :)

Sort of, but probably not in a way you’d like. If you look at the second page of the datasheet, you’ll see a graph relating responsivity and wavelength. Assuming red == 700nm and blue == 450nm, you’re looking at ~0.8 and 0.6 relative responsivity.
Whether that’s enough to be discernible by your control system is up to you and your design.

obviously that is not possible as it heavily depends on the luminance of the object. i suggest buying 3, and buying 3 markers, a red blue and green marker. Those make sure only resp. red blue and green light passes through. jippy problem solved.

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